The use of fortifiers to improve the properties of epoxy resins is disclosed in U.S. Pat. Nos. 4,739,028, 4,480,082 and 4,816,533, the disclosures of which are incorporated herein by reference.
In addition, the use of fortifiers to improve bismaleimide resins is disclosed in our copending application, U.S. Ser. No. 430,864 (filed 23 Oct. 1989).
It has now been surprisingly discovered that selected "epoxy fortifiers" may be employed to prepare thermoset cyanate ester resins having improved flexural properties.